Manufacture of heat exchange tubing



Oct. 24, 1961 H. J. VENABLES m MANUFACTURE OF HEAT EXCHANGE TUBING FiledSept. 26, 1958 7 Sheets-Sheet 1 FIGJ IO 46 a 2 "g g g 65 3 I 41 r 6 ll:I i\ 62 I Is 9 e 27 A /k INVENTOR.

HERB RT I YENABLES III BY g zc n.

H is ATTORNEY Oct. 24, 1961 H. J. VENABLES m 3,005,253

MANUFACTURE OF HEAT EXCHANGE TUBING Filed Sept. 26, 1958 7 Sheets-Sheet2 INVENTOR.

HERBERT J. VENABLES 1J1 Hi5 ATTORNEY Oct. 24, 1961 H. J. VENABLES mMANUFACTURE OF HEAT EXCHANGE TUBING 7 Sheets-Sheet 3 Filed Sept. 26,1958 FIG-.4

INVENTOR.

HERB RT J. VENABLES JIL BY HIS ATTORNEY Oct. 24, 1961 H. J. VENABLES mMANUFACTURE OF HEAT EXCHANGE TUBING 7 Sheets-Sheet 5 Filed Sept. 26,1958 m R0. R5 N. n mm o0 B mwfm mo. M w: Mm m I m w: m 6 E H E m @E w mm ho. m B Q m r w. J ifi. i F: r 0 1 H V o k m w 5i M. a2 Ifi H & .81 vh. N: wz TV Q Q L 2 HIS ATTORNEY Oct. 24, 1961 H. J. VENABLES IllMANUFACTURE OF HEAT EXCHANGE TUBING 7 Sheets-Sheet 6 Filed Sept. 26,1958 FIGJO m R L W5 A MN 5 v I. T R E B R E H HIS ATTORNEY Oct. 24, 1961H. J. VENABLES 111 3,005,253

MANUFACTURE OF HEAT EXCHANGE TUBING Filed Sept. 26, 1958 Sheets-Sheet 7F'IG.H

li Ill! 5 Wllllll|||||||||||||||||||||"I!" i -i? 59 F I i v .v 7&\\ i1 W58 M 3 INVENTOR. 5 HERBERT :r. VENABLES I11 1 i BW HIS ATTORNEY UnitedStates Patent C) Filed Sept. 26, 1958, Ser. No. 763,514 Ciaims. (Cl.29-33) The present invention relates to the manufacture of finned tubingemployed for heat exchange purposes and has as its principal object theprovision of improved means for manufacturing heat exchange tubing ofthe type including a tubular member having helically wrapped thereon afin material formed into a plurality of individual fin sectionsextending outwardly from a base flange.

In known machines for making finned tubing having fins of this type, astrip of fin stock is slit from one edge to form a plurality ofindividual fin sections connected by a base flange, bending the finsections outwardly with respect to the base flange, and, while rotatingand advancing the tubing, wrapping the fin material onto the tubing withthe base flange in flat-wise engagement with the surface of the tubingand with the individual fin sections extending outwardly therefrom.These machines use suitable tension devices to avoid breakage of the finstock during wrapping. Because of the need for these tensioning devices,it has been necessary to rotate the tubing rather than the fin stock andthe fin forming mechanism due to the fact that centrifugal forces wouldinterfere with the proper operation of the tensioning means. As aresult, only short lengths of tubing could be wrapped, the length beinglimited to that which could be rotated as it passed through the wrappingmachine.

The machine of the present invention comprises a rotatable head forcarrying a coil of strip stock thereon and including an axial passagetherein through which a tubular member is advanced. The machine includesa means for reducing the exterior circumference of the tubular member inorder to provide a tube of continuously uniform circumference as it isadvanced through the axial passage in the rotatable head. Means areprovided on the head for removing strip stock from the coil and forforming the strip stock into a serrated fin material having an angularlydisposed base flange. Means are provided on the head for wrapping theserrated fin material onto the tubular member with the base flangedisposed in fiat-wise engagement with the circumference of the tubularmember as the rotatable head is rotated around the tubular member. Inorder to maintain a constant tension on the fin material while it isbeing wrapped onto the tubing, the fin material forming means isoperated at a rate to release fin material, for each revolution of thehead, that is a predetermined amount less than is demanded by thehelical wrapping requirement as constituted by the uniform circumferenceand governed lineal advancement of the tubular member.

For a better understanding of the invention, reference may be had to theaccompanying drawings in which:

FIG. 1 is an elevational view of the machine of the present inventionwith portions of the machine broken away; M

'FIG. 2 is a plan view taken along line 2 2 of FIG. 1 showing thedriving gear arrangement for driving the various components of themachine;

FIG. 3 is a plan view taken along line 3-3 of FIG. 1 showing the swagingrolls for reducing the circumference of the tubular member as is fedupwardly through the machine; A

FIG. 4 is a partial elevation view taken along line 4:-4 of FIG. 3 andillustrating the swaging and driving components;

FIG. 5 is a plan view looking downwardly on the ma- Patented Oct. 24,1961 chine as shown in FIG. 1 and illustrating the rotatable headcarrying the coil of fin stock;

FIG. 6 is a cross-sectional view of the rotatable head taken along line66 of FIG. 5;

FIG. 7 is a cross-sectional view taken along line 77 of FIG. 6, showingthe braking arrangement for preventing overrunning of the stock carryingtable;

I .FIG. 8 is a partial plan view taken along line 8--8 of FIG. 6 alsoillustrating the braking arrangement for preventing overrunning of thefin stock carrying table;

FIG. 9 is a detail view illustrating one of the friction brakes forproducing the drag on the coil carrying table with respect to therotatable head;

FIG. 10 is a detail view fin forming, slitting and wrapping mechanismcarried centrally on the wrapping head;

FIG. 11 is an elevation view taken along line 11-11 of l0 illustratingthe flange forming operation;

FIG. 12 is a partial cross-section taken along line 12-12 of FIG. 10illustrating the wrapping and tin sections straightening mechanism ofthe machine;

FIG. 13 is a schematic view illustrating the slitting operation and thetilt imparted to the fin sections during the operation;

FIG. 14 is a schematic view illustrating, in exaggerated form, theamount of fin material formed for a revolution of the head in relationto the reduced circumference of the tubular member; and

FIG. 15 is a greatly exaggerated cross-sectional view of a tubularmember showing the shape it assumes when wound in coils.

Referring to FIG. 1 there is shown a machine for manufa'ctur'ing heatexchange tubing of the type having a discontinuous fin. The machine issupported on a base or bench 2 which carries the machine for rotationabout a vertical axis. A suitable supply of tubular material, such asthe large coil 3a, provides tubular material 3 which is fed verticallyupward through the machine. Mounted within the base 2 of the machine isa tube feed and swaging assembly 4 which provides means for reducing thecircumference of the tubing as well as for driving the tubing upwardlythrough the remaining components of the machine. Arranged on a top plate6 of the base 2 is a drum supporting member 7 which supports a rotatabledrum or spindle 8 for rotation about a vertical axis. The upper end ofthe rotatable spindle 8 carries a rotatable head 9 which in turn carriesmeans for supporting a coil of sheet stock as well as a fin wrapping andforming assembly 10.

Means are provided for rotating the spindle 8 and, thereby, the head 9about the vertical axis of the spindle 8. More specifically, the spindle8 and the rotatable head 9 are driven by a motor 11 which, through abelt 12 or chain, supplies power to the main drive shaft 13. The shaft13 extends downwardly into a gear box and, through separate gear chains,drives the rotatable drum 8; as well as the tube feeding and swagingassembly 4 in the lower portion of the base 2. More specifically, as maybest be seen in FIG. 2, the shaft 13 provides power for rotating thespindle 8 through the large gear 14 which engages the gear 16 fixed onthe revolvable spindle 8. As may be seen in FIG. 1, the rotatablespindle 8 is supported within the vertical support 7 by means ofanti-friction bearings 17, which permit rotation of the drum and therotatable head when power is applied to the shaft 13. A tubular guide 19is disposed centrally within the spindle 8 and arranged to receive thetube 3 from the feed roll assembly 4 during the operation of themachine. The tubular guide 19 is rigidly and vertically supported by thetop plate 6 and extends upwardly through an axial passage formed in therotatable head 9. A bearing 18 provides support for the upper portion ofthe tubular guide which extends axially through the rotatable spindle onthe rotatable head 9.

Referring again to FIG. 2, in order to drive the tube feeding andswaging assembly 4, there is provided a gear chain including the smallgear 22 on the shaft 13 which drives an idler gear 23 keyed to a shaft24 which in turn drives a chain of gears designated 25, 26, 26a and 27.Gear 26 is shown partially broken away in FIG. 2 in order to show thatgear 27 is driven by the gear 2611 which is disposed below gear 26 andon the same shaft as gear 26. Gear 27 is secured to shaft 28 which isjournalled in the top plate 6 and extends downwardly into the base 2 fordriving the swaging and tube feeding assembly 4. As may be more clearlyseen in FIGS. 3 and 4, the shaft 28 extends downwardly into the tubeswaging and feed assembly 4 wherein it drives a set of swaging rolls,generally designated 29, and two sets of driving rolls designated 31 and32 (driving rolls 32 are not shown in FIG. 4). p

The shaft 28 carries three worms 33 which are in mesh with three wormgears 34, that directly connect with feed roll drive shafts 36 and applypower to the first roll in each set of feed or swaging rolls. As may beseen in FIG. 3 all of the swaging rolls 29a, 29b and 29c are positivelydriven through a plurality of bevel gears 37 which form a chain aroundthe swaging assembly 29. As may be seen in FIG. 3, the triangulararrangement of the three rolls 29a, 29b and 290 all positively driventhrough the bevel gear train, provides a compressive force substantiallyaround the entire periphery of the tube 3 which is fed upwardly throughthe swaging assembly 29. The set of swaging rolls 29a, 29b and 290 aredesigned to reduce a particular sized commercially available tubing,when passedtherethrough, to a more nearly uniform or constantcircumference. The purpose of the swaging operation will be more clearlyexplained later in this specification. It is contemplated that theswaging rolls be made of hardened steel or contain a hardened insertwhich willpermit a longer period of use. The assembly is also madeeasily removable and may be replaced when wear begins to reduce theaccuracy of the swaging operation.

the configuration of the tubing nor do they change the size which hasbeen obtained through the swaging or sizing assembly 29.

Tubing 3, after it has been sized in the swaging and tube feed assembly4, is fed into the tubular guide 19, as shown in FIG. 1. This leads thetubing upwardly through an axial passage in the rotating head 9 where itenters the fin forming and winding assembly 10. As may be best seen inFIGS. 1, 5 and 6 supporting'means are provided on the rotatable head 9for carrying the strip stock 41 in large circular-coils. In order topermit the strip stock to pay off of the coil 41 as the rotatable head 9is rotated about the tube 3 being advanced upwardly through therotatable head, it is necessary to provide means, rotatable with respectto the rotating head 9, that allows the strip stock 41 to pay off of thecoil. More specifically, there'is provided a coil carrying table 42which is mounted on the rotatable head 9 and which is free to rotatewith respect to the head. The coil of strip stock rests on the table andis clamped at its inner diameter so that, for all practical purposes,there is no slippage between the coil and the table. A plurality ofclamping dogs 45 secure the inner diameter of the coil stock withrespect to the support table 42. As may be seen in FIG. 6, the table ismounted on rollers 43 that are arranged at many points around therotatable head and coil. As may be seen in FIG. 5, the stock 41 passesaround an idler roll 44 and then enters into a'turret 46 in which ismounted the forming and wrapping assembly. The strip material is twisteddegrees after it leaves the idler roll 44 before it is pulled into theturret 46.

Referring to FIGS. 10, 11 and 12 there is shown, in greater detail, theforming and wrapping assembly which receives'the strip stock 41, formsit and wraps it onto the tubular member advancing upwardly through therotating head. Means are provided within the turret 46 for forming abase flange on the strip stock 41 and for lancing the strip inwardlyfrom one end to form'separate or discontinuous fin sections. The tubularguide 19 extends upwardly through a cavity or axial passage in therotatable head 9 and the turret 46 and directs the tubular member 3 intothe rotating wrapping assembly. At the upper end of the tubular guide isa fin straightening head (seen best in FIG. 12) generally designated 47.Associated with the fin straightening head 47 are means for wrapping theformed and slit fin material onto the tubular member 3 as itadvancesthrough the wrapping head. As the strip stock 41 enters the turret 46 itis directed by a guide 48 into the hem or flange forming means. In

the present invention, the flange forming means comprises a single passof three forming rolls having their axis in one vertical plane andconstituting a single line of tangency which describes a right angle.More specifically, the forming means comprises a lower roll 49, an upperroll 51 and a cone-faced roll 52. These rolls form the flat strip stock41 into a right angular section. As the strip stock 41 approaches theupper and lower rolls, which grip the stock along its major width theright hand edge of the strip 41, as seen in FIG. 11, abuts against theflange 53 on the upper roll 51 which serves to guide the strip throughthe forming rolls. As. the strip approaches the forming rolls, thecone-faced roll SZengages the left hand or the outwardly extending edgeof the strip material and. provides a continual trend or force againstthe free left edge of the strip stock 41. The resulting confinementcauses the free edge of the strip to roll clockwise until a commontangency is reached between a portion of the upper roll 51 and thecone-faced roll. The flange 53 on the upper roll 51 opposes thehorizontal component of force exerted by the conical roll 52 therebycausing compression of the strip 41 and assisting the formation of thehem 54. The above described hem 54 forming means also exerts a slightpull or tension on the strip stock- 41 for removing the stock from thecoil.

As the strip stock 41 leaves the hem forming means, itpasses through aguide 56, best seen in FIG, 10, and is directed into a means forslitting the major width of the stock into'a plurality of separate finsections. The'slitting means comprises an upper lancing or slitting roll57 and a lower lancing orslitting roll 58 (best seen in FIG. 11)

each of which contain a plurality of cutting teeth for slitting thestrip 41 from its right hand edge, as seen in FIG. 10, to a pointadjacent the hem 54 of the strip. As can be seen in FIG. ll, the hem 54of the strip, which has been turned upwardly with respect to theremaining portion of the strip stock, rides flush against the face ofthe upper lancing or slitting roll 57 while the remaining portion of thestrip stock is slit into a plurality of discontinuous fin sections 59. xI Y Means are provided for driving the forming and slitting rollsintimed relation with the rotation of the rotatable head 9. Morespecifically, as may be seen in FIG. 1, in order to drive the slittingand forming means, there isprovided' on the tubular guide 19, which, asstated before, remains stationary with respect to the rotatable head 9,a sun gear 60 having its gear teeth in mesh with a planetary gear 61journalled in the rotatable'he'ad. As the'head rotates about the tubularguide 19 and the sun gear 60, the gear 61is turned 'with respect to thehead 9 and it, in turn, imparts rotational power to the shaft 62journalled in the head; Upwardly from the gear 61 on the shaft 62 is agear 63 which meshes with a gear 64 and imparts rotation to a worm shaft65 extending upwardly into the turret 46. As may best be seen in FIG.10, the worm shaft 65 carries a worm 66 which meshes with the worm gear'67. Worm gear 67 rotates the lower lancing roll 58 (not seen in FIG.through a shaft (not shown) which lies directly below the upper lancingroll shaft 68 and which is exactly the same as the upper lancing rollshaft except that it carries a pinion gear 69 shown in dotted lines.Pinion gear 69 drives idler 71 and this in turn drives the gear 72(shown in FIG. 11) on shaft 73 to apply power to the lower forming roll49. Driving gear 74, also attached to the lower forming roll shaft 73and rotatable therewith, engages a gear 76 on the upper forming rollshaft 77 to drive the upper forming roll 51. The cone-faced roll isdriven by a means of a pair of intermeshing bevel gears 78 and 79mounted respectively on the face of the lower forming roll 49 and thecone-faced roll 52.

In the illustrated embodiment of the invention there is no direct powersupplied to the upper slitting roll 57. Instead, this roll is positionedsuch that it is driven through the fin stock by the cutting teeth of thelower slitting roll as these teeth slit the individual fin sections 59.In other words, as may best be understood by reference to FIG. 13, themeshing of the slitting teeth of the upper and lower slitting rolls 57and 58 respectively causes the upper roll 37 to be driven through thematerial by the lower slitting roll 57.

The strip material 41 after being formed into a plurality of separatediscontinuous fin sections 59 connected at the hem or flange portion 54is directed around a turn-around roll 86 which is journalled into thebottom of the turret. The turn around roll 86 is free to rotate with thefin material passing around its outer surface. After passing around theturn-around roll 86, the previously formed fin material is directed intoa means for winding the material onto the surface of the tube 3. Morespecifically,

' the fin stock or fin material passes through a guide 87 and is thenWrapped onto the tube as the tubing is advanced through the finstraightening head 47 of the tubular guide 19. All of the componentswithin the turret 46 are rotating, along with the rotatable head 9,around the tubular guide 19 and the tube 3 advancing upwardlytherethrough. The rotation of the head 9 causes the fin material to behelically Wound around the tube 3 as the tribe advances through the finstraightening head 47.

Referring now to FIG. 12, it may be seen that, as the tube advancesthrough the fin straightening head 47, it passes through an adhesivecavity 88 which applies to the surface of the tube a rubber base orother type adhesive for binding the fin material to the tube 3. Adhesiveis pumped or supplied to the adhesive cavity 88 through a feed tube 89.it should be mentioned that the inner diameter surface of the head 47 issplined to permit the adhesive to be retained on portions of the tubingas it passes therethrough while still providing annular support for thetubing during wrapping. As the tubing is fed up wardly through the finstraightening head 47, the strip or fin material is wound helically ontothe tube with the hem 54 or base section of the fin material inflat-wise engagement upon the surface of the tube 3 and With the hempointing upwardly. The adhesive squeezes out from between the tubing andthe hem and fills any space between adjacent wrappings of the material.

Referring now to FIG. 13 there is shown in exaggerated form, theslitting rolls 57 and 58 as they lance the individual fin sections 59.It should be note that each section 59 is canted at an angle withrespect to the original horizontal surface of the fin material 41. Ithas been found that these canted fin sections are not as desirable inthe finished heat exchange tubing as sections which are arranged topresent less resistance to air flow. Moreover, these canted fin sectionsmake the wrapping of the fin material somewhat diflicult in that theytend to hang up on each other and various components of the machine.Therefore, the present invention provides a means for straighteningthese individual fin sections with respect to the plane of the material.More specifically, there is provided on the fin straightening head 47 aninclined surface 91 which, in combination with a beveled surface 92a ofthe straightening roll 92, straightens the individual fin sections asthey pass between the surfaces. The straightening roll 92' rotatesaround the tubing, along with the remaining components of the turret andthe rotatable head 9, and is powered so that the edge 93 thereof isactually or practically stationary with respect to the surface of thetube directly adjacent thereto. That is, the straightening roll 92 ispoweredby a gearing arrangement which drives it at such a speed that theouter periphery or edge 93 of the straightening roll 92 is practicallystationary with respect to the surface of the tube. As each successivefin section is drawn toward the tubing 3 it is engaged by the conicalface 92a of the straightening roll 92. The fin sections are eachsuccessively passed between the surface of the straightening roll andthe inclined surface 91 of the fin straightening head and the cant ineach section 59 is ironed out by the twist imparted to each section 59due to the action of these two surfaces. It should be noted that thestraightening roll 92, although it runs flush with or brushes againstthe hem, does not exert any appreciable pressure on the hem against thetubing. That is, there is no compressive force or any other forceapplied to the fin material except the tension in the hem 54 of thematerial to cause the fin material to wind onto the tube 3. The roll 92only acts on the individual fin sections to straighten the tilt in thesesections during rotation of the roll about the tube 3.

In order to rotate the straightening roll 92 there is provided a gearingarrangement or means operated in timed relation with the rotation ofhead 9 and similar to that used for driving the forming and slittingmeans. This driving arrangement may best be seen in FIG. 11. Above thesun gear 60 on the upper end of the tubular guide 19 there is provided asecond, but smaller, sun gear 94. This engages a planetary gear 96 on ashaft journalled in the lower portion of the turret 46. Rotation of theplanetary gear 96, during the rotation of the rotatable head 9 andturret 46 around the tubular guide 19, operates a small pinion gear 97directly above the planetary gear 96. Pinion gear 97 drives a gear 98 onthe lower portion of the shaft 99 which, in turn, rotates the gear 101on the upper portion of the shaft 99; Gear 101 intermeshes with thepinion gear 102 of the straightening roll drive shaft 103. Drive shaft103 is mounted in an adjustable collar 104 to permit raising or loweringof the roll 92.

As stated before, the coil carrying table 42 rotates with the head 9 butis also supported on rollers to permit the table to rotate independentlyof the head 9 in order to pay off strip stock 41. In order to maintain apositive tension in the strip stock as it pays off of the coil and toassure rotation of the coil carrying table 42 with the rotatable head 9,means is provided for creating a drag or braking effect on the rotationof the support table 42 with respect to the head. By promoting a tensionin the strip stock 41 as it pays off of the coil, the coil is maintainedtightly Wrapped and prevented from uncoiling or hooping because of thecentrifugal force acting on the coil during rotation of the head. Morespecifically, there are provided a plurality of braking means arrangedin Archimedes fashion around the coil support table. As may be moreclearly seen in FIG. 9, each of these braking means comprises a frictionshoe 106 having its surface riding on the outwardly extending table 107of the rotatable head 9. Each of these friction shoes 106 is forceddownwardly against the table 107 by means of a plunger 108 which isdepressed into the support table 42 by'the coil of strip stock 41. Theplunger 108forces the spring 109 into greater compression and thiscauses the shoe 106 to 'does not exceed a predetermined value.

exert a'greater frictional force against the rotation of the coilcarrying table 42. 7

As may be seen in FIGS. '6 and 9', when the fin stock 41 pays oif fromthe coil and is removed from that portion of the support table 42 abovethe plunger 108, the plunger is forced upwardly by the spring 109releasing the compression of the spring and vastly reducing thefrictional drag of the shoe. As may be seen in FIG. 5, each of thesefriction brakes is arranged in an Archimedes spiral around the coilsupport table and the brakes are therefore, progressively, released asthe strip stock pays off of the coil. This, in turn, reduces the brakingforce on the table 42 as the strip stock is relinquished from the tablethus reducing the amount of pull necessary to remove strip stock fromthe coil. It is desirable to gradually reduce the amount of brakingforce on the table as the radius of the coil reduces in order tomaintain a nearly constant tension in the strip stock 41 as it pays offof the coil. If the braking force were not gradually reduced as thediameter of the coil decreases, the moment of force created by thetension in the strip stock and the radius of the coil would, then,necessarily have to be a constant force to overcome the braking effect.In such a case, the tension in the strip stock 41 would increase tocompensate for the gradual reduction in the radius of. the coil, and thetension in the strip stock 41 necessary to overcome the braking effectwould, when the diameter of the coil was greatly reduced, break thestrip stock. Furthermore, as the diameter of the coil reduces, thecentrifugal force on the individual loops of the coil reduces and thereis less tendency for hooping and this also reduces the amount of tensionneeded in the strip stock as it feeds from the coil. In passing, itshould be noted that the drag or braking effect created by thefrictional brakes has nothing to do with the tension provided forwrapping the fin material onto the tube. The wrapping tension isentirely provided by the forming means in a manner to be explained laterin this specification.

Since the table 42 is free to rotate with respect to the head and sincethe mass of the table is great, especially when carrying a full coil ofstrip stock 41, a tremendous rotational inertia exists in the rotatingsupport table 42 and it is necessary to provide some means forpreventing overrunning of the support table 42 when the rotatable head 9is being stopped. It should be mentioned that this momentum or inertia,tending to cause overrunning of the table, greatly exceeds the amount ofbraking force exerted by the frictional brakes 106 on the table 107.Thus, a positive braking force is necessary to prevent the overrunningof the table when it is necessary to stop the rotating head 9. This isprovided, as can best be seen in FIGS. 7 and 8, in the form of aneccentrically mounted circular wedge or camming brake 111 which is incontact with a brake flange 112 extending downwardly from the table 42.The camming brake 111 is arranged on a shaft 113 which extends throughthe table 107 of the rotatable head 9. On the opposite end of the shaft113 is a lever arm 114 which rotates the shaft 113 and the eccentricwedge 111. The lever arm 114 is biased in a direction to prevent brakingof the eccentric 111 by spring 116 connected in tension between theouter end of the lever arm 114 and the stud 117 extending from the lowersurface of the table of the rotatable head;

In operation, the eccentric camming brake is designed to permit theflange 112 to rotate with respect to the rotatable head 9, or withrespect to the table 107 on the rotatable head, as long as .the amountof friction Thus, the tension of the spring 116 through the lever arm114 exerts a force against the eccentric to permit the flange 112' torotate so long as the friction between the flange and the eccentric doesnot exceed'a predetermined value. I This permits a uniform relativelyslow feed off of strip stock 41. But, whenever there is a tendency forthe support table 42 to overrun the speed of thehead 9, the frictionbetween the flange 112 and the eccentric wedge111 overfor the materialand the material breaks. .cially true when the fin material has beenformed into comes the moment of force exerted by the spring 116 and thelever ar-m 114. The wedge or camming brake then immediately turns in adirection to stop the rotation of the support table 42. As the cammingbrake 111 turns, the flange 112 is wedged between the wedge 111 and theback up roller 118 on the opposite side of the flange and the increasedfriction developed between the eccentric and the flange 112 stops therotation of the support table 42 with respect to the head 9.

As stated previously, the forming means, or the hem flanging andslitting rolls, removes for each rotation of the head 9 a predeterminedlength of strip stock 41 from the coil and forms it into fin material.Referring to the schematic drawing of FIG. 14, it can be seen that theforming means, or the flanging rolls 49 and 51 and slitting rolls 57 and58 are purposely geared to remove from the coil of strip stock a lengthof strip stock equal to the amount A for one revolution of the head.This same length A of strip stock is formed into fin material andsupplied or released for wrapping during each revolution of the head.However, the projected helical length of one revolution about tubularmember is equal to the length designated B in FIG. 14. Of course, FIG.14 greatly exaggerates the difference C between the lengths A and B, butit is obvious from the drawing that the fin material must be elongatedor stretched between the forming means and the point where it is wrappedonto the tubing during the wrapping procedure. It should be pointed outthat, after a few revolutions of the head, the amount of elongation ofthe material between the forming means and the point of wrapping foreach revolution, or the amount C, is wrapped onto the tubular member foreach revolution of the head. That is, the percentage of elongation ofthe material between the forming means and the wrapping pointapproximates but never exceeds the percentage of elongation necessary towrap a length A, which is formed during one revolution of the head, ontothe helical length B of one revolution of the tubing. Therefore, bymaintaining the elongation C within the permissible limits of elongationof the fin material for one turn around the tube 3, it is possible tocontinuously wrap the fin material at a precalculated tension, i.e., thetension produced by the elongation. For example, it is contemplatedthat, for a inch diameter copper tubing, the forming means will releaseabout 1% less fin material for each revolution of the head than isrequired to completely wrap around the circumference of the tubing in ahelical fashion. This is approximately .012 inch less fin material thanis required to helically Wrap around the circumference of the tubing.Thus, in this case the length C amounts to .012 inch and this would, ona tubular member of constant circumference, produce a uniform tension.

Since the permissible elongation without rupture of certain types of finmaterial, such as certain kinds of com- 'mercially available aluminumstock, is between 1% or 2% of the circumference of inch tubing, orapproxi- 'mately .02 to .025 inch, it is necessary to prevent any morethan the desired 1% elongation of the fin material (i.e. .012 inch forinch tube stock) during wrapping to eliminate continual breaking of thefin material at some point between the forming means and the tubing.

However, commercially available copper tubing of inch diameter has aplus or minus two thousandths of an inch variation in diameter, and thisalone provides a variation of .012 inch in the circumference of thetubing. As stated previously, the tin material that is being presentedto the tubing is already maintained at a particular elongation ortension such as the .012. inch mentioned above for aluminum finmaterial, and, if the tubing runs at its maximum circumference for ashort period, the additional elongation of the material soon causes thematerial to exceed the permissible limit of elongation This isespeanemone 9 t a plurality of separate fin sections by slitting thematerial'from one edge to the narrow base flange or-hem. The slitting ofthe fin stock transversely to its length makes it more likely to tear,thus further reducingthe permissible elongation .of the strip material.

In order to permit a reasonable tension in .the material during wrappingit is necessary, therefore, to main"- tain the tubing at a very closediameter or circumference. This, of course, is accomplished 'by theswaging assembly 29. -In a tested embodiment of the present invention,the swaging rolls 29a, 29b and 290 reduce, for example, a We inch tubinghaving an average circumference of 1.178 inches to a tubing having acircumference-of1.168 inches plus or minus .002 inch. This is only.004inch variation on the circumference of tubing. When fin material isfed at the rate of 1.168 inches less 1% (.012) or at aproximately 1.156inches for each revolutionof the head, there is little danger ofexceedingnthe maximum permissible elongation of the material even thoughthe tubing might run at its maximum diameter of L170 inches for a longperiod. For greater diameters .of tubing and for dilferent materials offin stock the permissible amount of elongation of the fin material foreach wrap thereof onto the tubing may change. However, in' all. cases,it is first desirable to reduce th'ecircumference of thetubing to someconstant and uniform size so that the strip stock may be maintained at auniform tension while being wrapped onto the tubing.

A further and important function of the. swaging rolls 29, in additionto reducing the circumference oflthe tubular member 3, is to make themember more perfectly round. Tubing when wrapped into rolls takes on theconfiguration shown in exaggeratedcross section in FIG. 15. That is,whenever tubing is wrapped in rolls or bent, it flattens out into asomewhat elliptical shape. Inthis form it has a major diameter x and aminor diameter y and, if wrapped in this form, it causes a very uneventype of wrapping. For each revolution of the head the elliptical crosssection of such tubing causes two pulses which are the result of slightchanges in tension produced in the fin material due to the change inshape of the tubing. These pulses are sufficient at times to cause thefin material to rupture. Since it is more expedient to ship largequantities of tubing in roll form, the elliptical shape produced in thetubing is always present. in most commercially available tubing and theswaging rolls correct it.

Operation of the present machine is relatively simple and is veryefiicient in that great lengths of tubing are passed through the machinewhile .fin material is continuously wrapped thereon. When the supply offin ma terial is exhausted, a new coil of fin material. is loaded ontothe rotatable support table 42 and clamped into place. The end of thematerial is passed through the forming means and a few turns of materialare wrapped around the tubing and held thereon by the adhesive on thetubing. The wrapping operation then begins again. In order to supplysuffic-ient strip material for a long length of tubing it iscontemplated that the tube, upon being wrapped, will proceed upwardlyand axially through several coils of stored. strip stock 41. Uponexhausting of one coil of strip stock, another is lowered onto the tableand the tube need not be severed to permit the insertion of additionalcoils of fin stock 41.

By the present invention there has been provided a machine forcontinuously wrapping long lengths of tubing with a serrated finmaterial having discontinuous .fin sections. The machine is designedsuch that the tubing is passed through the machine axially withoutrotation while the wrapping and forming components of the machine arerotated around the tubular material. Moreover, the machine includes anarrangement for maintaining a uniform and precalculatedtension in the.fin material during wrapping which arrangement requires. notranslationally movable parts between the forming means and the pointwhere the fin material is wrapped onto the tubing.

While in. accordance with the patent statutes there has been, shownand-described what at present is considered to be the,preferredembodiment of the invention, it be obvious to those skilled inthe art that various changes and modifications may be made thereinwithout departing from the invention, and it is, therefore, the aim ofthe appendedclaims to cover all such changes and modifications as fallwithin the true spirit and scope of the invention.

What I claim is new and desire to secure by Letters Patentof the UnitedStates is:

l. A machine for manufacturing finned tubing of the type having aplurality ofindividual fin sections extending outwardly therefromcomprising a rotatable head having anaxially disposed passage therein,means for rotating said head, means, on said head for supporting a coilof strip stock'about said axial passage, said coil supporting meansbeing rotatable with respect to said head, means operated in timedrelation with the rotation of said head for reducing the exteriorcircumference of tubing to a uniform circumference and for advancingsaid tubing at a governedrate through said axial passage in saidrotatable head, forming means on said head for removing strip stock fromsaid coil and forming it into fin material havinga pluralityofindividual fin sections connecting at one endto abase flange, means onsaid head for directing said-fin material onto said tubing beingadvanced through said head thereby to wrap said fin material onto saidtubing as said head is rotated around said tubing with said base flangeof saidfinmaterial disposed in flat-Wiseengagement with said tubing andwith said individual fin sections extending radially outward therefrom,and means carried by said head for driving said forming means to releasea length of fin material for each revolution of said headthat is lessthan the length demanded for helical wrapping onto the uniformcircumference of said tubing I of strip stock about said axial passage,said coil supporting means being rotatable with respect to said head,swagingrolls'through which tubing is passed for reducing the exteriorcircumference of said tubing to a uniform circumference, feeding rollsoperated in timed relation with the rotation of said head for advancingsaid tubing at a predetermined rate through said axial passage in saidhead, forming means on said head for removing strip stockfrom said coiland forming it into fin material having a-plurality of indiwidual finsect-ions connecting at oneend'to a base flange, meanson said head fordirectingsaid fin material onto said tubing being advanced through'saidhead thereby to wrap said fin material onto said tubing as said head isrotated about said tubing with-said baseflange of said fin material inflat-wise engagement on said tubing and with said individual finsections extending radially outward therefrom, and means carried by saidhead for driving said forming means to release a length of fin materialfor each revolution of said 'head that is less than the length demandedfor helical wrapping upon the uniform circumference of said tubing beingadvanced through said axial passage by an amount within'the permissiblelimit of elongation of said "fin material for each wrap thereof ontosaid tubing so .that a predetermined tension is continuously maintained'insaid fin material.

3. A machine for manufacturing finned tubing of the typehaving aplurality of individual fin sections extending outwardly therefromcomprising a base, a rotatable head mounted for rotation above said baseand having an axially disposed passage therein, means for rotating saidhead, a tubular guide aflixed to said base and extending into said axialpassage in said rotatable head, means on said head for supporting a coilof strip stock about said axial passage, said co-il supporting meansbeing rotatable with respect to said head, a plurality of swaging rollsoperated in timed relation with the rotation of said head for engagingtubing around the circumference thereof and for reducing the exteriorcircumference of said tubing to a uniform circumference, a plurality offeed rollsoperated in timed relation with the rotation of said head andarranged between said swaging rolls and said tubular guide for directingsaid tubing into said tubular guide and for advancing said tubing at agoverned rate therethrough, forming and slitting rolls on said head forremoving strip stock from said coil and for forming it into fin materialhaving a plurality of individual fin sections connecting at one end to abase flange, means on said head for directing said fin material ontosaid tubing being advanced through said tubular guide into said headthereby to wrap said fin material onto said tubing as said head isrotated about said tubing with said base flange of said fin material inflat-wise engagement upon said tubing and with said individual finsections extending radially outward therefrom, and means carried by saidhead for driving said forming and slitting rolls to supply fin materialat a linear rate for each revolution of said head that is approximately1% less than is demanded by the uniform circumference of said tubing asit is advanced at a governed rate through said axial passage so that apredetermined tension is maintained in said fin material.

4. A machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a rotatable head having an axially disposed passage therein,means for rotating said head, means on said head for supporting a coilof strip stock about said axial passage, said coil supporting meansbeing rotatable with respect to said head, means operated in timedrelation with the rotation of said head for reducing the exteriorcircumference of tubing to a uniform circumference and for feeding saidtubing through said axial passage in said rotatable head, forming rollson said head for removing said strip stock from said coil and forforming a base flange thereon, slitting rolls on said head for slittingsaid strip stock transversely from one end thereof to form a pluralityof individual fin sections connecting at one end with said base flange,means on said head for directing said fin material onto said tubingbeing advanced through said head thereby to wrap said fin material ontosaid tubing as said head is rotated about said tubing, with said baseflange of said fin material in flat-wise engagement upon said tubing andwith said individual fin sections extending radially outward therefrom,and means carried by said head for driving said forming rolls and saidslitting rolls to supply fin material at a linear rate for eachrevolution of said head that is less than is demanded for helicallywrapping said fin material onto the uniform circumference of said tubingas it is advanced through said axial passage by an amount within thepermissible limit of elongation of said fin material for each wrapthereof onto said tubing so that a predetermined tension is continuouslymaintained in said fin material.

5. A machine for manufacturing a finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a rotatable head having an axially disposed passage therein,means for rotating said head, means on said head for supporting a coilof strip stock about said axial passage, said coil supporting meansbeing rotatable with respect to said head, means operated in timedrelation with the rotation ofsaid head for reducing the exteriorcircumference of tubing to a uniform circumference and for feeding saidtubing at 'a governed rate through said axial passage in said rotatablehead, base flange forming means upon said head for removing said stripstock from said coil and for forming a base flange thereon, said baseflange forming means including upper and lower forming rolls forengaging said strip stock along its major width with one edge of saidstock extended outwardly of said upper and lower forming rolls, acone-faced roll for engaging said outwardly extending edge of said stockand rolling it into confinement against the side face of said upper rollthereby forming a right anglebase flange thereon, slitting rolls on saidhead for slitting said strip stock transversely from one end to a pointadjacent said base flange toform individual fin sections connected atone end to said base flange, means on said head for directing said finmaterial onto said tubing being advanced through said head thereby towrap said fin material onto said tubing as said head is rotated aboutsaid tubing with said base flange of said fin, material in flat-wiseengagement upon said tubing and with said individual fin sectionsextending radially outward therefrom, and means carried by said head forrotatably driving said forming rolls and said slitting rolls to releasefin material at a linear rate for each revolution of said head that isapproximately 1% less than is demanded for helically wrapping said finmaterial onto the uniform circumference of said tubing as it is advancedat a governed rate through said axial passage so that a predeterminedtension is continuously maintained in said fin material.

6. A machine for manufacturing a finned tubing of the type having aplurality of individual fin sections extending radially outwardtherefrom, comprising a rotatable head having an axially disposedpassage therein, means for rotating said head, a tubular guide havingone end extending into said axial passage in said head through whichtubing is advanced into said rotatable head, means on said head forsupporting a coil of strip stock about said axial passage throughwhich'said tubing is advanced, said coil supporting means beingrotatable with respect to said head, swagin-g rolls disposed below saidtubular guide for engaging said tubing and reducing the exteriorcircumference of said tubing to a uniform circumference, a plurality offeed rolls arranged between said swaging rolls and said tubular guide,means for driving said swag-ing and feed rolls in timed relation withthe rotation of said head thereby to advance tubing at a predeterminedrate through said tubular guide, base flange forming means upon saidhead for removing strip stock from said coil and for forming a baseflange thereon, said base flange forming means including upper and lowerforming rolls for engaging said strip stock along its major width withone edge of said stock extended outwardly of said uppm and lower formingrolls, a cone-faced roll for engaging said outwardly extending edge ofsaid stock and roiling it into confinement against the side face of oneof said rolls to form a right angled base flange thereon, slitting rollson said head for slitting said strip stock transversely from one edge toa point adjacent said base flange to form individual fin sectionsconnecting at one end with said base flange, means on said head forhelically wrapping said fin material onto said tubing being advancedthrough said head with said base flange in flat-wise engagement uponsaid tubing and with said individual fin sections extending radiallyoutward therefrom as said head is rotated about said tubing, and meanscarried by said head for rotatably driving said forming rolls and saidslitting rolls to supply fin material at a linear rate for eachrevolution of said head that is approximately 1% less than is demandedfor helically wrapping said fin material onto the uniform circumferenceof said tubing as said tubing is advanced through said axial passage sothat a predetermined tension is maintained in said fin material. I

7. A machine for manufacturing finned tubing of'the type having aplurality of individual fin sections extending outwardly therefromcomprising a base, a hollow rotatable spindle supported above said basefor rotation about a vertical axis, a rotatable head on the upper end ofsaid spindle, said rotatable head having an axially disposed passagetherein, means for rotating said spindle md thereby said rotatable head,a tubular guide extending upwardly through said rotatable spindle intosaid axial passage in said rotatable head, said tubular guide beingstationary with respect to said spindle and rotatable head, means onsaid head for supporting a coil of strip stock about said axial passage,said coil supporting means being rotatable with respect to said head,swaging rolls within said base for engaging tubing and for reducing theexterior circumference of said tubing to a uniform circumference, aplurality of feed rolls arranged between said swaging rolls and saidtubular guide for advancing said tubing at a governed rate through saidtubular guide and said axial passage, gearing means operated in timedrelation with the rotation of said spindle and said head for drivingsaid swaging rolls and feed rolls to advance tubing upwardly throughsaid tubular guide at a predetermined linear rate, forming and slittingrolls on said head for removing strip stock from said coil and formingit into fin material including a plurality of individual fin sectionsconnecting at one end to a base flange, means on said head for directingsaid fin material onto said tubing being advanced through said headthereby to Wrap said fin material onto said tubing as said head isrotated around said tubing with said base flange of said fin material inflat- Wise engagement on said tubing and with said individual finsections extending radially outward therefrom, and means carried by saidhead for driving said forming and slitting rolls to release fin materialfor each revolution of said head at a linear rate that is approximately1% less than is demanded for helically wrapping said fin material ontothe uniform circumference of said tubing as it is advanced at a governedrate through said axial passage so that a predetermined tension iscontinuously maintained in said fin material.

8. A machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a rotatable head having an axially disposed passage therein,means for rotating said head, means on said head for supporting a coilof strip stock about said axial passage, said coil supporting meansbeing rotatable with respect to said head, means operated in timedrelation with the rotation of said head for reducing the exteriorcircumference of tubing to a uniform circumference and for advancingsaid tubing at a governed rate through said axial passage in saidrotatable head, forming rolls on said rotatable head for removing stripstock from said coil and for forming a base flange thereon, upper andlower slitting rolls on said head for slitting strip stock transverselyfrom one end to a point adjacent said base flange to form a plurality ofindividual fin sections connecting at one end with said base flange,means on said rotatable head for guiding said fin material onto saidtubing being advanced through said head thereby to wrap said finmaterial onto said tubing as said head is rotated about said tubing withsaid base flange of said fin material in flat-wise engagement on saidtubing and with said individual fin sections extending radially outwardtherefrom, and means carried on said head and operated in timed relationwith the rotation of said head for driving at least one of said slittingrolls to release fin material at a linear rate for each revolution ofsaid head that is approximately 1% less than is demanded for helioallywrapping said fin material onto the uniform circumference of said tubingas it is advanced at a governed rate through said axial passage so thata predetermined wrapping tension is maintained in said fin material.

9. A machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending radially outwardtherefrom, comprising a base, a hollow spindle supported by said basefor rotation about a vertical axis, a tubular guide fixedly secured tosaid base and extending upwardly through said rotatable spindle, arotatable head carried by said spindle and having an axially disposedpassage into which said tubular guide extends, means for rotating saidspindle and thereby said rotatable head, means on said head forsupporting a coil of strip stock about said axial passage, said coilsupporting means being rotatable with respect to said rotatable head, aplurality of swaging rolls in said base below said tubular guide, meansfor driving said swaging rolls in timed relation with the rotation ofsaid spindle for reducing the exterior circumference of tubing to auniform circumference and for advancing said tubing upwardly at agoverned rate through said tubular guide into said rotatable head, baseflange forming means on said rotatable head for removing strip stockfrom said coil and for forming a base flange thereon, said base flangeforming means including upper and lower forming rolls for engaging saidstrip stock along its major width with one edge of said stock extendingoutwardly of said upper and lower forming rolls, a cone-faced roll forengaging said outwardly extending edge of said stock and rolling saidedge into confinement against the side face of said upper roll to form aright angled base flange on said strip stock,

slitting rolls mounted on said head for slitting said strip stocktransversely from one end to a point adjacent said base flange to form aplurality of individual fin sections connecting at one end with saidbase flange, a sun gear around the outer periphery of said tubular guideadjacent said rotatable head, means on said rotatable head for guidingsaid fin material onto said tubing being advanced through said headthereby to wrap said fin material onto said tubing as said head isrotated about said tubing with said base flange of said fin material inflat-wise engagement on said tubing and said individual fin sectionsextending radially outward therefrom, and a gear train driven by therotation of said rotatable head about said sun gear for rotatablydriving said forming rolls and said slitting rolls to supply finmaterial at a linear rate for each revolution of said head that isapproximately 1% less than is demanded for helically wrapping said finmaterial onto the uniform circumference of said tubing as said tubing isadvanced into said rotatable head so that a predetermined tension ismaintained in said fin material.

10. A machine for manufacturing finnedtubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a rotatable head having an axially disposed passage therein,means for rotating said head, a coil support table on said head forsupporting a coil of strip stock about said axial passage, said coilsupport table being rotatable with respect to said head, means operatedin timed relation with the rotation of said head for reducing theexterior circumference of tubing to a uniform circumference and foradvancing said tubing at a governed rate through an axial passage insaid rotatable head, forming and slitting rolls on said head forremoving strip stock from said coil and forming it into fin materialincluding a plurality of individual fin sections connecting at one endto a base flange, means on said head for directing said fin materialonto said tubing being advanced through said head thereby to wrap saidfin material onto said tubing as said head is rotated about said tubingwith said base flange of said fin material in flat-wise engagement onsaid tubing and with said fin sections extending radially outwardtherefrom, means carried by said head for driving said forming andslitting rolls to release fin material at a linear rate for eachrevolution of said head that is approximately 1% less than is demandedfor helically wrapping said fin material onto the uniform circumferenceof said tubing as said tubing is advanced through said axial passage sothat a predetermined tension is maintained in said fin material andbrake means between said support table and said rotatable head '15 .forretarding the rotation of said support table with respect to saidrotatable head thereby to maintain a predetermined tension in said stripstock as it is fed from said coil on said table to said fin formingmeans.

11. A machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a base, a hollow spindle supported on said base for verticalrotation thereon, a rotatable head carried by said spindle and having anaxially disposed passage therein, means for rotating said spindle andthereby said head, a support table mounted on rollers above saidrotatable head for permitting the rotation of said table with respect tosaid head, said table supporting a coil of strip stock about said axialpassage in said head, means operated in timed relation with the rotationof said head for reducing the exterior circumference of tubing to auniform circumference and for advancing said tubing at a governed ratethrough said axial passage in said rotatable head, fin forming means onsaid head for removing strip stock from said coil and for forming itinto fin material including a plurality of individual fin sectionsconnecting at one end to a base flange, a plurality of brake meansarranged in an archimedes spiral around said coil support table, each ofsaid brake means having a friction shoe engaging the upper surface ofsaid rotatable head, plunger means associated with each of said brakemeans for forcing said friction shoe into engagement'with said rotatablehead when strip stock is carried on said table above each of said brakemeans, said brake means retarding the rotation of said table withrespect to said head thereby to provide a predetermined tension in saidstrip stock when said strip stock is fed from said coil, each of saidbrake means releasing its brake shoe as the radius of said strip stockdecreases sufficiently to provide clearance above said plunger meansthereby to gradually decrease the amount of force required to rotatesaid table with respect to said head, means on said head for directingsaid fin material onto said tubing being advanced through said headthereby to wrap said fin material onto said tubing as said head isrotated around said tubing with said base flange of said fin material inflat-wise engagement on said tubing and with said fin sections extendingradially outward therefrom, means carried on said head for driving saidfin forming means to release fin material at a linear rate for eachrevolution of said head that is approximately 1% less than is demandedfor helically wrapping said fin material onto the uniform circumferenceof said tubing as said tubing is advanced through said axial passage sothat a predetermined tension is continuously maintained in said finmaterial.

12. A machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a rotatable head having an axially disposedpassage throughwhich tubing is advanced, means for rotating said head, means on saidhead for supporting a coil of strip stock about said axial passagethrough which said tubing is advanced, said means including a horizontalsupport table supported on rollers above said head, an overrunning brakemeans for preventing overrunning of said table with respect to saidrotatable head as the speed of rotation of said head is reduced, saidoverrunning brake meansincluding a circular flange extending downwardlyfrom the bottom of said coil support table, a friction responsivewedging mechanism mounted on saidrotatable head and engaging saiddownwardly extending flange, said friction responsive wedging mechanismpermitting slow rotation of said table in one direction with respect tosaid head to permit normal feed off of strip stock from said coil Whilepreventing rotation of said table in the other direction with respect tosaid head by wedging against said downwardly extending flange, meansoperated in timed relation with'the rotation of said head for reducingthe exterior circumference of tubing to a uniform circumference and foradvancing said tubing at a governed rate through said axial passage insaid rotatable head, fin forming means for removing strip stock fromsaid coil and forming it into fin material including a plurality ofindividual fin sections connecting at one end to base flange, and meanscarried on said head for driving said fin forming means to release finmaterial at a linear rate for each revolution of said head that isapproximately 1% less than is demanded for helically wrapping said finmaterial onto the uniform circumference of said tubing as said tubing isadvanced through said axial passage so that a predetermined tension ismaintained in said fin material.

13. A machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a base, a rotatable head mounted for rotation above said baseand having an axially disposed passage therein, means for rotating saidhead, a tubular guide aflixed to said base and extending into said axialpassage in said rotatable head, means on said head for supporting a coilof strip stock about said axial passage, said coil supporting meansbeing rotatable with respect to said head, a plurality of swaging rollsfor engaging tubing around the circumference thereof and for reducingthe exterior circumference of said tubing to a uniform circumference, aplurality of feed rolls arranged between said swaging rolls and saidtubular guide for directing said tubing into said tubular guide and foradvancing said tubing at a predetermined rate therethrough, said swagingand feed rolls being operated in timed relation with the rotation ofsaid head, fin forming means on said head for removing strip stock fromsaid coil and for forming it into fin material having a plurality ofindividual fin sections connecting at one end to a base flange, means onsaid head for driving said fin forming means to supply fin material at alinear rate for each revolution of said head that is approximately 1%less than is demanded for helically wrapping said fin material onto theuniform circumference of said tubing as it is advanced through saidtubular guide into said axial passage, a fin straightening head mountedon the end of said tubular guide, said fin straightening head having aninclined surface adjacent which said fin material is wrapped onto saidtubing with said base flange in flat-Wise engagement upon said tubingand with said individual fin sections extending radially outwardtherefrom as said head is rotated about said tubing and a straighteningroll carried on said head, said straightening roll having a surfacecooperating with said inclined surface on said fin straightening headfor straightening said individual fin sections as said fin material isdirected onto said tubing. 7

14. In a machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a base, a hollow spindle mounted above said base for verticalrotation thereon, a rotatable head carried on the end of said hollowvertical spindle, said rotatable head having an axial passage therein,means for rotating said spindle and thereby said head, a tubular guideaffixed to said base and extending axially upward through said hollowspindle into said axial passage in said rotatable head, means in saidbase operated in timed relation with the rotation of said head forreducing the exterior circumference of tubing to a uniform circumferenceand for advancing said tubing upwardly at a governed linear rate throughsaid tubular guide into said rotatable head, means on said head forsupporting a coil of strip stock about said axial passage through whichsaid tubing is advanced, said coil supporting means being rotatable withrespect to said head, forming means upon said head for removing stripstock from said coil and for forming a base flange thereon, said baseflange forming means including upper and lower forming rolls forengaging said strip stock along its major width with one edge of saidstock extending outwardly of said upper and lower forming rolls, acone-faced roll for engaging said outwardly extending edge of said stockand rolling it into confinement against the side face of said upper rollthereby forming a base flange thereon, slitting means on said head forslitting said strip stock transversely from one edge to a point adjacentsaid base flange to form individual fin sections connected at one end tosaid base flange, means carried by said head for rotatably driving saidforming rolls and said slitting rolls in timed relation with therotation of said head to release fin material for each revolution ofsaid head that is approximately 1% less than is demanded for helicallywrapping said fin mateii-al onto the uniform circumference of saidtubing as said tubing is advanced through said tubular guide into saidrotating head, -a fin straightening head mounted on the end of saidtubular guide, said fin straightening head having an inclined surfaceadjacent which said fin material is Wrapped onto said tubing with saidbase flange in flat-wise engagement with said tubing, a straighteningroll carried on said head and rotatable therewith, said straighteningT0111 cooperating with said inclined surface on said fin straighteninghead for engaging opposite sides of each of said individual fin sectionsand straightening said sections as said fin material is wrapped ontosaid tubing and means carried by said head for rotatably driving saidstraightening roll in timed relation with the rotation of said head.

15. In a machine for manufacturing finned tubing of the type having aplurality of individual fin sections extending outwardly therefromcomprising a rotatable head having an axially disposed passage therein,means for rotating said head, means on said head for supporting a coilof strip stock about said axial passage, said coil supporting meansbeing rotatable with respect to said head, means operated in timedrelation with the rotation of said head for reducing the exteriorcircumference of tubing to a uniform circumference and for advancingsaid tubing through said axial passage in said rotatable head, baseflange forming means on said head for removing said strip stock fromsaid coil and for forming a base flange thereon, slitting rolls on saidhead for slitting said strip stock transversely from one end thereof toform a plurality of individual fin sections connecting at one end withsaid base flange, means on said head for directing said fin materialonto said tubing being advanced through said head thereby to wrap saidfin material onto said tubing as said head is rotated about said tubingwith said base flange of said fin material in flat-wise engagement uponsaid tubing and with said individual fin sections extending radiallyoutward therefrom, and means carried by said head for rotatably drivingsaid slitting rolls in timed relation with trespect to the rotation ofsaid head so that said slitting rolls release a length of fin materialfor each revolution of said head that is less than is demanded forhelically wrapping said fin material onto the uniform circumference ofsaid tubing as said tubing is advanced through said axial passage insaid rotatable head by an amount within the permissible limit ofelongation of said fin material for each wrap thereof onto: said tubingso that a wrapping tension is continuously maintained in said finmaterial.

References Cited in the file of this patent UNITED STATES PATENTS336,899 Davis Mar. 2, 1886 1,883,222 VVoOd Oct. 18, 1932 1,960,517Taylor May 29, 1934 2,167,971 Cadden Aug. 1, 1939 2,199,594 Kent May 7,1940 2,303,760 Rafter Dec. 1, 1942 2,364,736 McGlone Dec. 12, 19442,472,245 Busse June 7, 1949 2,532,239 Newlin Nov. 28, 1950 FOREIGNPATENTS 811,081 France Apr. 6, 1937

